“I can’t imagine not getting up and being here,” she said on the air. Roberts also told viewers she’d check into the hospital on Tuesday but that it would be 10 more days before the transplant — via a donation from her sister, Sally — would actually take place.

In advance of Roberts’ departure, this week “Good Morning America” will highlight other stories of people afflicted by MDS, the rare blood disorder Roberts was diagnosed with this spring.

The announcement this morning was not a huge surprise, at least not to fans who follow the host on Twitter. Over the weekend, Roberts tweeted that she had left her dog K.J. in the care of some friends and had “cried like a baby.”

As Roberts explained on the air, the handoff was necessary because “when you have a bone-marrow transplant, you don’t have an immune system for a while and you’re very susceptible to infection.”

Roberts had just returned to the show Aug. 20 after taking an abrupt vacation.

"My needle was past 'E' when I left here a couple of weeks ago, but I’ve got a full tank, so watch out," she said upon her return last week. "I haven't taken this much time off in quite some time."